“I called my vegetable trader and told him I don’t want any Spanish products,” said Nour, referring to the warning by Hamburg authorities that cucumbers from Spain appeared to be the source of the contamination — a claim they have since retracted.

“That was easy enough. Then it turns out it wasn’t from Spain. So it’s hard to know what to do," he said.

“People came in saying, ‘Can I have a sandwich without the salad?’ I can’t just delete the salad. In the end I made a compromise and kept the salad but left out cucumber.”

As of Wednesday, 17 people were dead, more than 400 were seriously ill and more than 1,500 were confirmed affected by the bacteria, which lives in the guts of warm-blooded mammals. As the mystery deepened as to the source of the outbreak, much of the rest of Germany was either frightened, frustrated or plain bewildered.

At least 200 new cases were reported on Wednesday. Adding to the worries, this particular strain of E.coli, called O104H4, is particularly aggressive, causing violent hemolytic uremic syndrome, which leads to bloody diarrhea, kidney failure, coma and death.

Doctors in the northern state of Schleswig-Holstein, which has been hardest hit, reported that it is also causing unusual neurological issues, ranging from speech problems to epilepsy.

Denis Coulombier, head of surveillance and response for the European Centre for Disease Prevention and Control, which monitors disease in the region, said health experts are shocked by the “huge contamination.”

That contamination could have happened "anywhere from the farm to the fork," he said. “It's certainly something we haven't seen before in the EU and probably in the world.”

The initial claim that three Spanish cucumbers bore traces of the deadly bacteria has been retracted. The cucumbers did contain E.coli, but not the O104H4 strain.

German health authorities went back to the drawing board and began their search anew. In the meantime, food suppliers in Germany, Denmark, the Czech Republic, Luxembourg, Hungary, Sweden, Belgium and Russia were stopping entry of Spanish cucumbers, Spanish media reported. Russia banned vegetable imports altogether from both Spain and Germany.

Spanish officials, unsurprisingly, were livid and threatened legal action against the Hamburg city-state government, claiming its farmers have lost 200 million euros ($288 million) from the stampede away from their products. (A loss Spain, no doubt, can ill afford.)

Aside from the mix-up over the Spanish cucumbers, the warnings from the Robert Koch Institute, the government’s top public health adviser, have been consistent for days: people in northern Germany, where the cases have been overwhelmingly concentrated, should avoid cucumber, uncooked tomatoes and lettuce.

What becomes clear from speaking to shoppers on the streets of Berlin, though, is that the words “Spain” and “cucumber” have stuck in people’s minds.

“I’m not buying cucumbers, but they’re now saying Spanish vegetables are okay,” said Heidi Mussler, 37, who was carrying grocery bags out of a supermarket in the Prenzlauerberg district of Berlin. “I don’t know where these come from,” she added, pointing to the fresh lettuce and other vegetables among her groceries.

When it’s explained to her that nobody knows the source of the E.coli and that the authorities can no longer rule anything in or out, Mussler resolved simply to cook everything thoroughly.

Another shopper, 44-year-old Frank Weber, said he didn’t much like cucumbers anyway, so that was no great loss, but he was “being careful.”

“It does sound like a really terrible thing to get," he said. "Mostly I’m preparing things carefully, washing everything and cooking it. Salad? Maybe, if I could be sure where it came from. I saw the Spanish politician eating a cucumber to show it was okay. Let me say this: I wouldn’t give anything like that to my kids.”

Maher Abdel Nour said his vegetable trader was struggling to move his produce.

“He said he usually sells 40 boxes of lettuce,” he explained. “This week he’s sold 10.”